from the 4.2 simulation
// global attributes:
:title = "GOTM Simulation" ;
:history = "Created by GOTM v. 4.1.0" ;
:Conventions = "COARDS" ;
:_Format = "classic" ;
On Wed, Jan 18, 2012 at 09:15:34 -0600, Ted Mansell wrote:
> Does the recompile switch on netcdf4 features, or is it still writing a
> classic nc3 file using the nc4 libs? Just to clarify -- Not that I know if
> that makes a difference.
>
> -- Ted
>
> On Jan 18, 2012, at 2:10 AM, Karsten Bolding wrote:
>
> > Hello
> >
> > I'm working on a 1D ocean model that stores its output in NetCDF.
> >
> > With NetCDF4 I've experienced some performance issues as shown in the
> > timings below for a specific model run:
> >
> > NetCDF4:
> > real 0m42.940s
> > user 0m3.630s
> > sys 0m0.110s
> >
> > NetCDF 3.6.3:
> > real 0m1.838s
> > user 0m1.820s
> > sys 0m0.000s
> >
> > Its run on the same system only recompiling the executable to link
> > either NetCDF 3 or 4.
> >
> > Disk performance is not an issue:
> > /dev/sda:
> > Timing buffered disk reads: 344 MB in 3.02 seconds = 114.06 MB/sec
> >
> > as the resulting file is only 10MB.
> >
> > I'm using the 4.2 release candidate configured as follows:
> >
> > C:
> > CPPFLAGS=-I/opt/hdf5/include LDFLAGS=-L/opt/hdf5/lib ./configure
> > --prefix=/opt/netcdf-${netcdf_ver}_IFORT
> >
> > Fortran:
> > FFLAGS="-O3" FC=ifort F77=ifort CPPFLAGS=-I/opt/hdf5/include CFLAGS="-O3"
> > LDFLAG S=-L/opt/hdf5/lib ./configure
> > --prefix=/opt/netcdf-${netcdf_ver}_IFORT
> >
> > i.e. no specific optimisation.
> >
> > Netcdf 3.6.3 is also compiled without specific optimisation.
> >
> > Any ideas anyone?
> >
> > Karsten
> >
> > PS: I've done the above simulations a number of times with consistent
> > results.
> >
> >
> > --
> > ----------------------------------------------------------------------
> > Karsten Bolding Bolding & Burchard ApS
> > Strandgyden 25 Phone: +45 64422058
> > DK-5466 Asperup Fax: +45 64422068
> > Denmark Email: karsten@xxxxxxxxxxxxxxxxxxxx
> >
> > http://www.findvej.dk/Strandgyden25,5466,11,3
> >
> > Q: What is irony?
> > A: Almost the same as goldy and bronzy - just made of iron ...
> > (from Blackadder)
> > ----------------------------------------------------------------------
> >
> > _______________________________________________
> > netcdfgroup mailing list
> > netcdfgroup@xxxxxxxxxxxxxxxx
> > For list information or to unsubscribe, visit:
> > http://www.unidata.ucar.edu/mailing_lists/
>
>
--
----------------------------------------------------------------------
Karsten Bolding Bolding & Burchard ApS
Strandgyden 25 Phone: +45 64422058
DK-5466 Asperup Fax: +45 64422068
Denmark Email: karsten@xxxxxxxxxxxxxxxxxxxx
http://www.findvej.dk/Strandgyden25,5466,11,3
Q: What is irony?
A: Almost the same as goldy and bronzy - just made of iron ...
(from Blackadder)
----------------------------------------------------------------------
